Air-Duct Cleaning

If they're from Maryland then they're stinkbugs. They tend to colonize in an out-of-the-way place (attics, behind furniture, definitely in ducting if they can get in) and reproduce and, as luv2dsgn mentioned, bombing or just spraying them with Raid will not kill them, the tough little buggers. Best is to pull out every drawer and check the undersides for the colonies, then shop-vac everything, get the hose up into the furnace ducting and even under the air conditioner housing. I've seen some products here in Maryland that say they are specifically designed to kill stinkbugs, but I'm not sure how effective they might be, especially with pets in the coach. Don't crush them or the reason for their name will become annoyingly obvious - a friend of mine nailed it when he described the smell as "a really green fart."

If you can't get a shopvac hose into the duct, consider sticking an air compressor hose into a narrow duct to blow whatever's inside down to the end of the duct where you might get better access.